Microaerophilic–aerobic sequential batch reactor for treatment of azo dyes containing simulated wastewater

Sandhya, S.; Padmavathy, S.; Swaminathan, K.; Subrahmanyam, Y. V. B. K.; Kaul, S. N.

doi:10.1016/j.procbio.2004.02.015

Cited by 109 publications

(61 citation statements)

References 21 publications

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“…Several studies have demonstrated that the decolorization of azo dyes is enhanced under micro-aerophilic conditions (Joshi et al, 2008;Sandhya et al, 2005;Xu et al, 2007). An accelerated degradation of reactive azo dyes has been observed under partially reduced conditions (Khalid et al, 2012).…”

Section: Biodegradation Via Reduction Processmentioning

confidence: 99%

Bacterial diversity and composition in major fresh produce growing soils affected by physiochemical properties and geographic locations

Ibekwe

Yang

et al. 2016

Science of The Total Environment

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Azo dyes and their intermediate degradation products are common contaminants of soil and groundwater in developing countries where textile and leather dye products are produced. The toxicity of azo dyes is primarily associated with their molecular structure, substitution groups and reactivity. To avoid contamination of natural resources and to minimize risk to human health, this wastewater requires treatment in an environmentally safe manner. This manuscript critically reviews biological treatment systems and the role of bacterial reductive and oxidative enzymes/processes in the bioremediation of dye-polluted wastewaters. Many studies have shown that a variety of culturable bacteria have efficient enzymatic systems that can carry out complete mineralization of dye chemicals and their metabolites (aromatic compounds) over a wide range of environmental conditions. Complete mineralization of azo dyes generally involves a two-step process requiring initial anaerobic treatment for decolorization, followed by an oxidative process that results in degradation of the toxic intermediates that are formed during the first step. Molecular studies have revealed that the first reductive process can be carried out by two classes of enzymes involving flavin-dependent and flavin-free azoreductases under anaerobic or low oxygen conditions. The second step that is carried out by oxidative enzymes that primarily involves broad specificity peroxidases, laccases and tyrosinases. This review focuses, in particular, on the characterization of these enzymes with respect to their enzyme kinetics and the environmental conditions that are necessary for bioreactor systems to treat azo dyes contained in wastewater.

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Section: Biodegradation Via Reduction Processmentioning

confidence: 99%

Bacterial diversity and composition in major fresh produce growing soils affected by physiochemical properties and geographic locations

Ibekwe

Yang

et al. 2016

Science of The Total Environment

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show abstract

“…In addition, over 10,000 different dyes are known and have their applications in various industries. Studies indicate that approximately 10 % of synthetic dyes produced per year are lost to the environment during manufacturing and processing operations (Sandhya et al 2005). Dyes are classified according to their application and chemical structure.…”

Section: Introductionmentioning

confidence: 99%

Destruction of azo dyes by anaerobic–aerobic sequential biological treatment: a review

Popli

Patel

2014

Int. J. Environ. Sci. Technol.

239

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Dyes are synthetic organic compounds widely used in various industries such as, textile, leather, plastic, food, pharmaceutical, and paints manufacturing industries. Coloured effluents are highly toxic to the aquatic life and mutagenic to humans. Wastewater containing dyes has become an important issue demanding serious attention. Among the synthetic dyes, azo dyes are the largest and most widely used dyes and account for more than half of the annually produced dyes. The biodegradation of azo dyes is difficult due to their complex structure and synthetic nature. Several treatments have been proposed for efficient azo dye removal, most of them presenting some limitations such as generation of waste sludge, high operational costs, poor efficiency, and incomplete mineralization. Biological treatment is a cost-effective and eco-friendly process for dye degradation. Sequential anaerobic-aerobic biological treatment is considered as one of the most cost-effective methods for the complete mineralization of azo dyes. The anaerobic stage yields decolourization through reductive cleavage of the dye's azo linkages, resulting in the formation of generally colourless but potentially hazardous aromatic amines. The aerobic stage involves degradation of the aromatic amines. It is the most logical step for removing the azo dyes from the wastewater. Several factors can influence the microbial activity and consequently the efficacy and effectiveness of the complete biodegradation processes. This paper summarizes the results of biological decolourization of azo dyes using various types of reactors, elaborates biochemical mechanisms involved, and discusses influence of various operational parameters on decolourization based on reports published in the last decade.

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“…The ability of the facultative microorganisms to break down azo-bonds in azo dyes used in textile industry, under low aeration conditions has been documented [117]. Azo compounds resist the oxidative degradation by aerobic bacteria [118], due to the chemical structure of the N=N azolinkage.…”

Section: Degradation Of Recalcitrant and Toxic Organics Using Aeratiomentioning

confidence: 99%

“…Azo compounds resist the oxidative degradation by aerobic bacteria [118], due to the chemical structure of the N=N azolinkage. These compounds can however be reduced under either strict anaerobic or partially aerated conditions by the action of strict anaerobic or facultative anaerobic organisms [117]. This reduction process generates aromatic amines [119] which can be completely degraded by aerobic biodegradation.…”

Section: Degradation Of Recalcitrant and Toxic Organics Using Aeratiomentioning

confidence: 99%

Oxygen Effects in Anaerobic Digestion – A Review

Botheju¹,

Bakke²

2011

TOWMJ

133

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This article reviews the experimental and theoretical studies conducted on the possible effects of oxygen in biogas generating anaerobic digesters. The interactions of oxygen with various biochemical processes associated with anaerobic digestion are discussed together with other relevant aspects. The conventional perception of oxygen being merely toxic in anaerobic digestion (AD) is refuted. Digesters can withstand significant levels of oxygenation without drastic negative impacts. Limited quantities of oxygen can even lead to improved AD reactor performance under certain operating conditions. Co-existence of anaerobic and aerobic cultures in a single bioreactor environment has been demonstrated. It is shown that the partial aeration assisted AD can serve as a beneficial treatment strategy for simultaneous waste treatment and energy generation, for a multitude of organic waste categories.

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Microaerophilic–aerobic sequential batch reactor for treatment of azo dyes containing simulated wastewater

Cited by 109 publications

References 21 publications

Bacterial diversity and composition in major fresh produce growing soils affected by physiochemical properties and geographic locations

Bacterial diversity and composition in major fresh produce growing soils affected by physiochemical properties and geographic locations

Destruction of azo dyes by anaerobic–aerobic sequential biological treatment: a review

Oxygen Effects in Anaerobic Digestion – A Review

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